Numerous types of toy balls are known which are made of various synthetic materials. For example, U.S. Pat. No. 4,772,019 discloses a composite safety ball having a polyurethane foam core which is designed to replicate the performance of a regulation baseball or softball. U.S. Pat. No. 3,927,882 discloses a soccer ball which has a polyethylene core and an inner nylon cover. U.S. Pat. Nos. 3,616,101 and 3,490,770 disclose liquid center balls, such as golf balls, in which the central portion is a liquid polymer such as polyvinyl chloride. Due to the nature of the materials from which these types of balls are made, and the manner in which they are made, these types of balls are not resiliently deformable to the extent that they would provide a soft, supple feel when squeezed.
Other materials are known which possess resilient or elastomeric properties. For example, U.S. Pat. Nos. 4,369,284 and 4,618,213 are directed to elastomeric gelatinous compounds which may be molded into toy balls. The particular compounds disclosed in the '284 and '213 patents are poly(styrene-ethylene-butylene-styrene) triblock copolymers. While balls made of these types of materials are resilient, they possess an extremely high percentage of plasticizing oil, which tends to bleed or leach out of the ball body. This is undesirable because the user of the ball tends to get plasticizer all over himself and the ball may become brittle and subject to tearing or cracking as it loses plasticizer.